GM Performance Parts 350ci/330HP Crate Motor Build

We Get More Power Out Of A GMPP Crate Motor With Goodies From Brodix, Lunati, And Speed-O-Motive.

John Barkley, one of our associates here at Super Chevy, just recently did a little horse-trading and ended up with a fresh GM Performance Parts (GMPP) 350ci/330HP crate motor. He is an avid hot rodder and was a successful drag racer for many years (he even has a Wally in his trophy case from winning the Stock Eliminator class at the 1983 Winternationals). John is constantly building something, and his most recent project is a '66 Bel Air that could use some more power under the hood. He plans on using the car for cruising and light track duties. Even though the GMPP 330hp crate motor would motivate his land yacht of a car just fine, we would rather have the big ship run more like a small flat bottom drag boat.

2/17

We set John loose with the task of finding a solid upgrade for his engine that didn't require special machining or messing with the rotating assembly. He contacted Brodix for one of the company's top end kits, to take out the guesswork when it comes to finding components that work with each other. Brodix combines a set of the company's IK (Iron Killer) 180cc aluminum heads with a matching dual plane intake manifold, and all the little things like gaskets and hardware needed for the swap.

The heart of the Brodix top end kit are the heads; these feature ultra casting, 180cc intake ports, and 64cc combustion chambers that allow the use of several types of fuels. All these improvements over the stock heads are in place to increase the airflow. The more air the engine can ingest, the more power it can make. There are a bunch of options Brodix offers on these heads like 58-74cc CNC chambers, and just about anything else your deviant mind can think up, so keep that in mind when ordering. The Brodix kit comes with a dual plane intake big enough to support the heads, and for a small extra fee match ported as well.

For the valvetrain, John went with components from Lunati's Voodoo line, most notability a solid roller cam. John has always used hydraulic cams in his street motors, but wanted to try a solid roller this time. The cam spec's out at 0.555-int./0.566 exh. lift, 261 int./267 exh. advertised duration, 231 int./237 exh. duration at 0.050, with a 110-degree lobe center. He coupled the cam with a set of vertical bar roller lifters and 1.5 ratio Voodoo aluminum roller rockers. John went with this combo to be safe, not knowing how much piston to valve clearance it was going to have with the GMPP stock pistons. During testing we found this cam to be too small, but more on that later.

To feed the new heads, one of Holley's 750cfm Ultra Double Pumper street/strip carbs was tasked with fuel delivery. It's a 4150 design, but has black anodized billet aluminum metering blocks and base plate, mechanical secondaries, and surprisingly enough, an electric choke-not something normally found on a double pumper. To provide the spark, a ready to run billet HEI distributor from MSD was called to action. Since firewall clearance is not an issue, going with the coil-in-cap design and modern electronics were a no brainer. To assemble all of John's goodies and tune the engine on the dyno, we enlisted the help of the Speed-O-Motive crew in Covina, California. Don't get us wrong, we made John get his hands dirty on this project, but Jeff Strech from Speed-O-Motive also got involved. It was like watching an NHRA pit crew ripping down a motor between runs.

MORE PHOTOS

VIEW FULL GALLERY

xclose

GM Performance Parts 350ci/330HP Crate Motor Build

The main part of the top end combo is the IK (Iron Killer) 180cc aluminum heads and Horsepower 1 (HP 1) dual-plane intake manifold. The heads are the most budget-friendly in the Brodix line, cast from A-356 virgin aluminum alloy with 2.02 intake and 1.60 exhaust valves, normally with 64cc combustion chambers (ours were ordered with 60cc chambers to keep the compression up), phosphorous bronze valve guides, hardened valve seats, milled and drilled ends for accessories, and a straight spark plug angle. The HP 1 manifold has an operating range of idle-6,000 rpm, and the dual plane design will provide a good torque curve. John spent a little extra money to have Brodix match port the manifold to the heads for an unrestricted transition.

Since the combo is a complete kit, you also get all the other stuff needed for the install like the tall cast aluminum valve covers (breather holes will need to be added), head bolts, washers, intake bolts, valve cover hardware, head gaskets, intake gaskets, exhaust gaskets, carburetor gaskets, valve cover gaskets,...

...NGK spark plugs, and even a Brodix hat.

All the valvetrain components were ordered from Lunati, and include the solid roller cam, lifters, 1.5 ratio roller rockers, full double-roller timing set, and a cam thrust button. The timing set features three different keyways (+/- 4-degrees) and Torrington thrust bearing. The cam thrust button (necessary with any roller cam) keeps the camshaft from walking forward in the block, for accurate timing and to prevent premature timing chain and distributor gear wear.

For the cam, John stepped out of his normal routine and went with a solid roller instead of a hydraulic. He decided to play it safe and get himself a small Voodoo cam (part no. 60130) that has 0.555 int./0.566 exh. lift, advertised duration of 261 int./267 exh., and duration at 0.050 of 231 int./237 exh., with a 110-degree lobe center.

John also got a set of Lunati's vertical bar (tie-bar) roller lifters to ride on the cam. The lifters for John's engine are 0.300 inches taller for use in later model GM ('87-up) "roller" style blocks with taller lifter bores.

Finishing off the valvetrain is a set of Voodoo 1.5 ratio, 3/8-inch stud aluminum roller rockers. According to Lunati's website, these aluminum rockers are the product of extensive testing, including special deflection and high RPM simulations. They come completely assembled with poly locks.

For the carb, John looked to Holley and picked up an Ultra Double Pumper fuel sprayer. Not only does it look killer with black anodized, billet aluminum metering blocks and base plate, it has an enhanced fuel curve and 4-corner idle. Other notable details include mechanical secondaries, clear fuel level sight plugs, 1 timed (spark) port, 1 full vacuum, 1 PCV port, and an electric choke.

To light the fire, a GM-style HEI billet distributor, wires and separators were ordered from MSD. We won't need the wires until the engine goes in the car, as Speed-O-Motive already uses MSD wires on its dyno. Since John has plenty of firewall clearance, the simple coil-in-cap design of the HEI was a simple choice. Unlike a junkyard unit, the MSD HEI has a digital module and hot coil to provide plenty of spark energy.

With the carb and ignition installed on the out-of-the-box GMPP 350ci/330HP crate motor, the timing was set to 34 degrees total advance, then the engine was broken in. Once Jeff was confident everything was ready, he did an initial low rpm pull. Everything looked good, so he did a full pull and noticed the air/fuel ratio was off. After a few jet and power valve changes, he got it nailed and clicked off the results listed on the next page. As advertised, the engine laid down 335 hp and 372 lb-ft at the peaks. It was pretty much out of steam at 5,200 rpm, but still not too shabby for a low-buck crate motor.

All the stock stuff was ripped off in true pit crew fashion, and the new Brodix and Lunati components installed. Having all the correct gaskets, bolts, and so on really made this a quick swap on the dyno.

The one thing we have not mentioned so far are the pushrods. Since each motor can be different, it's hard to include a correct size pushrod with so many variables. The ones we used were supplied by Speed-O-Motive, and measure 8.050-inch on the intake side and 8.100-inch on the exhaust. Since this is now a solid roller motor, Jeff set the initial/cold valve lash to 0.010. Then he fired it up, let the engine come up to temp, and re-adjusted them to 0.016 lash while everything was hot.

Now it was time to see just what all these goodies produced...

...Again, after a couple of pulls to figure out the carb tuning and perfect timing, Jeff did a full pull, this time to 6,000 rpm. The new components let the engine breath better, allowing for more power at higher rpm.

The new combo netted us 362 hp and 384 lb-ft at the peaks, and another 800 rpm of usable power. Unfortunately, 27 hp and 12 lb-ft is a small gain, but we know exactly what the problem is-too small a cam. We already have a larger Lunati solid roller (lift 0.582, advertised duration of 276 int./284 ext., duration @ 0.050 of 243 int./251 exh., with a 110 lobe center) on the way for later testing, so stay tuned.